Question

x + 9y=33

5x + 4y =1

Answer 1

Eq1: X + 9Y = 33.

Eq2: 5x + 4y = 1.
Multiply both sides of Eq1 by -5 and add the Eqs:

Eq1: -5X - 45Y = -165.
Eq2: 5X + 4Y = 1.
Sum: 0 - 41Y = -164,
Y = 4.
In Eq1, substitute 4 for y:
X + 9*4 = 33,
X = 33 - 36 = -3.

Solution set: (X,Y) = (-3,4).